1. Field of the Invention
The invention relates generally to methods for linking data during recording encoded data on a recordable type optical disk, and more particularly to using an error correction code of the Cross Interleave Reed-Solomon Code (CIRC) type.
2. Description of the prior Art
In optical disks, and particularly in compact disks, namely audio compact disks (CD-audio) or read-only memory CDs (CD-ROM), the pieces of data that are to be recorded on the disk are encoded by using a specific modulation code, notably the EFM (Eight to Fourteen Modulation) code, well known to those skilled in the art. Furthermore, to correct the errors that occur on a disk, an error correction code which, in this case, is the CIRC, is associated with the EFM code. This error correction code enables the correction of most of the errors that occur on the disk, by carrying out an interleaving of the data. Owing to the use of these different codes, as well as the addition of parity or control bits, the data originally having a certain number of bits, is recorded on the disk with larger number of bits. Furthermore, due to the nature of interleaving along the position of the last few bits is not know with precision, because these bits are not recorded sequentially.
According to present compact disk standards, to enable easy synchronization of the pieces of data recorded on the disk, they are divided into frames which are grouped in blocks of p frames. In the ROM-CD or audio-CD standard, each frame is formed by 24 bytes and one byte of sub-codes, and each block is formed by 98 frames or 2352 bytes. All the sub-codes of the 98 frames constitute a frame of sub-codes. The interleaving due to the error correction code uses 108 frames at the most. The interleaving does not raise any problems in the case of a CD-ROM format or CD-audio format, because the data is recorded only once. This recording is done by the manufacturer
A problem of linking data arises when it is desired to use the same type of error correction code on a rewritable type of optical disk or a "Write Once" disk, where data is to be written at least once by a user. But, the interleaving for the error correction code does not facilitate the linking of the data. It is necessary to have a relatively large number of redundant blocks so as to be sure of recording all the data on this disk. This also increases the access time.
It is an object of the present invention, therefore, to provide a data-linking method during recording, on a recordable type of optical disk, of data encoded according to a specific coding using a CIRC error correction system which makes it possible to limit the number of redundant blocks necessary for the recording of each group of data.